Releasable screw driver



Dec. 13, 1949 v G. E. McvEY 2,491,325

RELESBLE SCREW DRIVER I Filed Jan. 22, 1945 I ,20v ,JN

Patented Dec. 13, 1949 UNITED STATES PATENT CFFICE RELEASABLE SCREWDRIVER Gerald McVey, Columbus, liio Application January 22, 1945, SerialNo. 573,843

4 Claims. l

This invention relates to screw drivers and has for its object toprovide a novel type of screw driver in which the shank of thescrewengaging bit element is rotatably mounted in. the receiving sockettherefor provided in the handle member, there being a spring-pressedclutch device. arranged between the bit element and one of the walls ofthe handle member socket operative upon the application of apredetermined rotating force to the handle member to release the bitelement to preclude rotation thereof until such rotating force isdiminished.

In the ordinary screw driver, the shank of the bit element is iixed tothe handle member to rotate in unison therewith under all conditions.Under certain conditions of screw driver usage, this conventionalVconstruction is undesirable'. Often, when too great a rotating force isapplied to a screw driver when threading a screw into an appliedposition, the force so eX- ercised results in damaging the work intowhich the screw is being driven. Therefore, the present inventionprovides a screw driver in which the bit element thereof is-formed witha bore adapted for the reception ci a springmressed ball, a portion ofthe latter being normally seated in a socket or depression provided inthe handle member of the tool, the spring-pressed ball acting as a slipclutch in uniting the bit element with the handle member, in that whenrotating forces are applied to the handle member below a given value,the bit element will rotate in unison with said handle member, but whensuch forces reach or exceed said value, the clutch-like ball isdisplaced from its normally seated position, allowing the handle memberVto turn freely with respect to the bit element and thereby interruptingrotation of the latter.

For an undersanding of other objects and advantages of the invention,reference is to be had to the following description and accompanyingdrawings, wherein:

socket l, in which is tightly driven a metallic sleeve t, one end of thelatter being closed as at Q while the other end thereof is formed withan annular outwardly extending ange i9, the outer face of the latterbeing formed with a substantially semicircular depression i l.

The bit element provides a shank IZ, the outer portion of whichterminates in a screw-engaging extremity I3 shaped to enter the headslots of standard or special type screws. The lshank l2, intermediatelyof its length, is provided with an enlarged head it, which is annularly`flanged as at i5 for engagement with the flange Il) of the socket l, andbeyond thek head ifi the bit element includes a cylindrical extension i6which is received in the bore of the sleeve 8, the end of the extensionI6 preferably engaging with an anti-friction thrust bearing il confinedin the sleeve 3 adjacent to the closed 9' thereof. The bit element isheld in connection with the handle member by providing the latter with a.errule in, thek latter having one end thereof formed with an inturnedcircular flange ES which receives and confines the `fia-nge it oli-.hcbit ele-i nient head Hi. The ferrule is non-rotatablysecured totheflange portion it' of thesleeve il' by means of one or more set screws,shown at To rotatably unite the handle `ir-.er-.iber 5 with the bitelement iso that the same normally rotate together,but to permit thehandlernembei to rotate independenti?,-7 of the bit element whenpredeterminedtorque eiort is applied thereto, the head M of the bitelement is lfoi ed with a diagonally extending bore El intersecting thelongitudinal axis thereof. Adapted to be. re ceived in the, inner end cithis bore is a mica-'- able clutch ball 22. A part of this ball isnormaily seated in the` depression H of the sleeve iiange Ell. and tomaintain the ball thus seated.

se is made of an expansion type coil spring 23, the latter beingpositioned in the bore 2i, with one end engaging the ball 22 and theoppcsite end in contact with a slidabie plunger 2li. One or more setscrews 2% are threaded irthe outer end of the bore 2i, and throughadjustment of these screws, the desired degree of spring pressure may beexerted on the ball 22.

From the foregoing, it will be seen that the.

present invention provides a torque-type screw driver which is adaptedfor use in the same manner as a conventional screw driver having the bitelement and handle members immovably united. However, with the screwdriver formed as above described, it will be evident that when apredetermined amount of rotating energy is. imparted to the handlemember, the ball 22,

that the principles thereof are applicable to` tools driven by electricmotors or the like.

Having thus described my invention, I claim: 1. A safety slip clutchcomprising a driving member formed at one end with an axially disposedsocket, a sleeve stationarily positioned in said socket, said sleevebeing closed at one end and having its opposite end formed with alaterally directed annular flange, a driven element having ashankextension rotatably received within said sleeve, a thrust bearingpositioned between one end of said extension and the closed end of saidsleeve, said driven element being formed intermediately of its lengthwith a flanged head enlargement, the flange of said eniargement beingdisposed for engagement with the iianged end of said sleeve, a ferruleremovably secured to said sleeve and cooperative with the flange of saiddriven element enlargement to retain said element in connection withsaid driving member, said enlargement being formed with a borediagonally intersecting the longitudinal axis of the enlargement, a balldevice positioned in one end of said bore for engagement with a,depression provided in the anged end of said sleeve, an eX- pansionspring positioned in said bore for maintaining said ball device normallyin engagement with said depression, and threaded means positioned insaid bore for regulating the force exercised by said spring on said balldevice.

2. A safety slip clutch comprising a driving member formed at one endwith an axially disposed socket, a driven element having a shankextension rotatably received Within said socket, said driven elementintermediately of its ends being formed with a head enlargement having abore diagonally intersecting in its length the longitudinal axis of thedriven element, a ball device positioned in said bore for engagementwith a depression provided in said driving member to cause rotation ofthe driven element in unison with said driving member upon predeterminedtorque conditions, a spring positioned in said bore in engagement withsaid ball device, threaded means positioned in said bore for varying theforce exercised by said spring on said ball device, and a ball-typeythrust bearing arranged between said shank extension and the closed endof said driving member socket, said bearing relieving said ball deviceof thrust loads.

3. A safety slip clutch comprising a driving member formed at one endwith an axially disposed socket, a driven element having a shankextension rotatably received Within said socket, said driven elementintermediately of its ends being formed with a head enlargement having abore diagonally intersecting in its length the longitudinal axis of thedriven element, a ball device positioned in said bore for engagementwith a depression provided in said member to cause rotation of thedriven element in unison with said driving member under determinedtorque conditions, a spring positioned in said bore in engagement withsaid ball device, and threaded means positioned in said bore for varyingthe force exercised by said spring on said ball device.

4. A safety slip clutch comprising a driving member formed at one endWith an axially disposed socket, a sleeve stationarily positioned insaid socket, said sleeve being closed at one end and open at its other,the open end of said sleeve being provided with an annular flange, adriven element having a shank extension rotatably received within saidsleeve, an antifriction thrust bearing positioned between one end ofsaid extension and the closed end of said sleeve, said driven elementbeing formed intermediately of its length with a flanged head-formingenlargement, the latter being provided With a bore which in the lengththereof diagonally intersects the longitudinal axis of the enlargement,a detent positioned in one end of said bore for engagement with adepression provided in the flanged end of said sleeve, a spring meanspositioned in said bore for maintaining said detent normally inengagement with said depression, and threaded means positioned in saidbore cooperative with said spring means for regulating the forceexercised by the latter on said detent.

GERALD E. MCVEY.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 998,615 Haneke July 25, 19111,246,554 Cotterman et al. Nov. 13, 1917 1,328,087 LeChot Jan. 13, 19201,394,795 Sauve Oct. 25, 1921 1,456,148 Sands Aug. 28, 1923 1,684,345Centeno Sept. 11, 1928 1,829,421 Roe Oct. 27, 1931

